Dyeing mixed fabrics



bichromates and acetic acid.

* PATENT OFFICE 2,212,628 DYEING MIXED FABRICS Hermann Winkeler, Lndwigshafen L on the Rhine, Germany, assignor to General Aniline & Film Corporation, a corporation of Delaware No Drawing. Application September 24,1937, Serial No. 165,511. In Germany October 10,- 1936 1 4 Claims.

The present invention relates to an improved method of dyeing mixed fabrics.

When dyeing mixed fabrics of animal and vegetable fibres, such as mixed fabrics of wool with cotton or regenerated cellulose, attempts are frequently made to increase the fastness properties of the dyeings, especially their fastness to moisture, by treatment with chromates or bichromates, as for example by the action of alkali A process which is especially easily carried out in practice and therefore frequently employed is the so-called half-wool metachrome process according to which the dyeing is carried outin the presence of ammonium sulphate and alkali metal chromate. In this case either substantive dyestuffs capable of being chromedand which are equally well taken up by animal and vegetable fibres are used or' mixtures of substantive dyestuffs with wool dyestuffs capable of being chromed and which dye only the woolin the mixed fabric.

There is no fundamental diiference between the two said dyeing processes; the chromates and bichromates are reduced to salts of trivalent chromium to which the chroming action is due. In both cases the wool portion of the mixed fabrics is dyed sufliciently fast, but the dyeings on the vegetable portion of -the mixed fabrics have only an insuflicient fastness to water.

I have now found that when dyeing mixed fabrics of animal and vegetable fibres with substantive dyestuffs capable of-being chromed or' with mixtures of such dyestuffs with wool dyestuii's capable of being chromed especially valuis also possible to treat the fibre dyed with the.

said dyestuffs in a separate bath with achromate or bichromate and simultaneouslywith a salt of trivalent chromium. Finally, the procedure may consist in treating the fibre in the same bath with the said. dyestuffs andja salt of chromic acid, adding a salt of trivalent chromium towards the end of the treatment. In the last case, it is preferable to use, for rinsing the dyeing. hot water to which has been added soap or another wetting or dispersing agent. 1

Among chromium salts suitable for the proposed treatment theremay be mentioned for 5 example the fluoride, sulphate, formate, acetate,

oxalate of trivalent chromium or mixtures of the said salts.

The improvement of the fastness to water,

Example 1 I A mixed fabric 015.70 per cent of wool and 30 per cent of viscose artificial silk is dyed in a bath with a bath ratio of 1:40jwith 3 per cent of the azo dyestufi derived from 1 molecular proportion of tetrazotized 4.4'-diaminodiphenyl urea and 2 molecular proportions of salicylic acid with an addition of 1 per cent of sodium chromate and 2 per cent of ammonium. sulphate in the' following manner: the bath is brought during the course of half an hour to 90 0., kept for 1 hours at the said temperature and the fabric allowed to remain in the cooling bath for an hour. Both kinds-of fibre are thus dyed rather uniformly in greenish yellow shades which have a moderate fastness to moisture. The dyed fabric is then treated for half an hour with 2 per cent of chromic sulphate or chromic formate (calculated with reference to the weight of the fabric). the fastness properties thus being improved to an extraordinary extent.

A fabric dyed in an equally fast manner may ,also be obtained by adding chromic formate to the dyebath towards the end of the dyeing process and shortly soaping the dyeing at about 40 C.

' Example 2 A mixed fabric of 30 per cent of wool and 70 per cent of viscose artificial silk is dyed in the manner described in Example 1 with the dyestuff derived from 1 molecular proportion of tetrazotized 4.4-diaminodiphenyl-3 3'-dicarbox- :ylic acid, 1 molecular proportion of l-hydroxynaphthalene-5-sulphonic acid and 1 molecular proportion of 2-phenylamino-5-hydroxynaphthalene-l-sulphonic acid (coupled alkaline). .In this way violet shades are obtained which have a slight fastness to washing and water. By aftertreating the dyed fabric for half an hour with 2 per cent of chromic sulphate (calculated with. reference to the weight of fabric) dyeings having considerably improved fastness to washing and.

excellent fastness to water are obtained.

Example 3 A mixed fabric of 30 per cent of wool and 70" per cent of viscose artificial silk is dyed intlie manner described in Example 1 with thedyestuff derived from 1 molecular proportion of tetrazotized 4.4-diaminodiphenyl, 1 molecular proportion of salicylic acid and 1 molecular proportion of a 2- (paracresotinsulphonyl) amino 5 hydroxynaphthalene-7-sulphonic acid (coupled a1- kaline) having the following formula:

(1)11 COOH may then be employed for being coupled withthe diazonium salt without further purification). Yellowish red shades of bad fastness to washing and entirely insufficient fastness to water are obtained. By aftertreatment of the fabric for half an hour with 2 per cent of chromium sulphate (calculated with reference to the weight of the fabric) somewhat more bluish dyeings are ob tained havinggreatly improved fastness to washing and excellent fastness to Water.

Example 4 A mixed fabric of '70 per cent of wool and 30 per cent of staple fibre (Zellwolle) is dyed according to the metachrome process with a mixture of the substantive dyestufi of the formula and the dyestufi obtainable by coupling diazotized 3.4.6-trichlor-2-amino 1 hydroxybenzene with sulphonic acid from greenish-blue to navy blue shades being obtained. By treating the fabric thus dyed in a separate bath with 2 per cent (calculated on amount of fabric) of chromifluoride, the fastness to washing, perspiration, water and fulling is remarkably improved.

Dyeings having similar good properties are obtained if 2 per cent of chromium sulphate are added to the metachrome bath towards the end of the dyeing process and then treating the dyeing in a; further bath for from 15 to 20 minutes with Marseille soap at from 40 to 50 C.

It is also possible to dye the fabric with the said dyestufl mixture from a neutral or weakly acid bath, then to effect the formation of the complex chromium compound in the usual manner by adding from 2 to 3 per cent of sodium bichrornate and then to aftertreat the fabric in a fresh bath with 2 per cent of chromium sulphate.

The dyeings obtained in the first bath may also be treated in a second bath with between 2 and 3 per cent of sodium bichromate in the presence of 2 per cent of acetic acid, and from 2 to 3 per cent of chromium sulphate.

What I claim is:

1. A process of dyeing mixed fabrics of animal and vegetable fibres with substantive azo dyestufl's capable of being chromed which comprises treating the fibre on which the said dyestuffs are already reacted with a salt of chromic acid, with a salt oftrivalent chromium in a separate bath.

2. A process of dyeing mixed fabrics of animal and vegetable fibres with substantive azo dyestuffs capable of being chromed which comprises treating the fibre with the said dyestuffs and first with a salt of chromic acid and in the same bath with a salt of trivalent chromium added towards the end of the treatment.

3. A process of dyeing mixed fabrics of animal and vegetable fibers with substantive azo dyestufi's capable of being chromed which comprises applying the dyestuffs to the fabric, treating the fabric with an aqueous solution of a chromic acid salt and then treating the fabric with a salt of trivalent chromium;

4. The process of claim 3, wherein the azo dyestuif applied to the fabric contains a salicylic acid radical in its molecule.

HERMANN WINKELER.

l-acetylamino s hydroxynaphthalene-4 

